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International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 Evaluation of Electric Generation from Energy Using Piezoelectric Actuator

Mohana Faroug Saeed Attia1, Afraa Ibraheim Mohmmed Abdalateef2

1Department of , University of Dongola, Sudan

2Collaborator Instructor University of Khartoum, Sudan

Abstract: This paper presents the done on the conversion techniques and methodologies of converting sound energy to its electrical counterpart, and focuses on the future of this type of energy sources than wind energy, , and biogas. Also, it includes the increase in due to ever growing number of electronic devices, and the harvesting energy from humans and using of piezoelectricity. In the experimental work, a piezoelectric generator lead zirconate titante (PZT actuator) is used to extract sound energy from the loudspeaker from various distances and then to convert this energy into . The maximum voltage generated by the piezoelectric generator occurs when its resonant frequency is operating near the frequency of sound. The result shows that the maximum output voltage of 28.8 mVrms was obtained with the of 80.5 dB resonant frequency of 65 Hz at 1 cm distance in the first mode. In the second mode, the maximum output voltage of 94 m Vrms was obtained with the sound intensity of 105.7 dB at resonant frequency of 378 Hz at 1 cm which is larger than that of the first mode. However, for both modes, voltage decreases as distance increases.

Keywords: piezoelectric effect, sound energy, piezoelectric material, resonant frequency, PZT actuator,

1. Introduction Piezoelectric materials have a crystalline structure that provides a unique ability to convert an applied mechanical The “law of ” states that energy strain into an electrical potential or vice versa. Our paper cannot be created nor be destroyed. Under the consideration includes how to utilize the energy which is wasted, creates of this law the technological giants have discovered pollution to the environment. The sound energy of the numerous sources to extract energy from them and use it as moving train wheels which is nothing but pollution can be a source of for conventional use.[1] converted into electrical energy with the help of piezoelectric material or transducer. Then this electrical There are various so called eco-friendly sources of energy energy will be saved with the help of a rechargeable DC that we have discovered till the present artificial era. Some source. This energy can be used to run a train compartment’s of them are implemented to great extent under the suitable lights and fans and other necessary purpose. Here we circumstances to overcome the short run of the energy due to discover the technology to generate from technological boom that has led the energy needs to its apex. sound of train wheels in which the system used is reliable [2] and this technique will help conserve our natural [5] resources.

Solar energy is one in the list that came up with the wide range of applications such as solar heaters, solar cookers and 2. Sound Energy it gained success due to its easy implementation. There are various other sources of which includes We all know sound energy is a which harassing energy form wind, , water etc. [3] travel in the form of wave, mechanical wave that is an oscillation of pressure which need medium to travel i.e. it Renewable energy sources such as , could not travel through vacuum as it need medium. and require high financial investments but give lower power output with respect to its cost. Another source Through liquid and gas state sound is transmitted as plant gives a good source of power butthe longitudinal wave whereas through solid it could be initial setting up and maintains costs are higher than other transmitted as both longitudinal wave and transverse wave.[6] renewable sources. In recent years, there has been growing interest in harnessing the power of mechanical vibrations Longitudinal waves are of alternating pressure deviation and pressure to generate electricity. from the equilibrium pressure, causing local region of compression and rarefaction, while transverse wave (in Piezoelectric materials play a vital role in generating power solid) are waves of alternating shear and stress at right angle which range is μW to mW. It is one of the most interesting to the direction of propagation, fig 1. When sound wave methods of obtaining the energy surrounding a system is to travel through a medium mater in that medium is use piezoelectric materials. This deformations produced by periodically displaced and thus oscillates with sound wave.[7] different means are directly converted to electrical charge via piezoelectric effect.[4] The sound wave displace back and forth between the of compression or lateral displacement strain of the matter and the of the oscillation.

Volume 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 218 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 engineer is interested in the accuracy of this transformation, a concept he thinks of as fidelity.[9]

The basic idea is that sound is mechanical wave. When sound travels through any medium then it disturbs the particles of that particular medium and these disturbances caused by the sound can be used to produce electricity.

The efficiency of the transducers and several such devices is quiet low and cannot be utilized for practical applications. Thus the major arena to focus is how we can increase the efficiency of the electricity produced by conversion of sound energy. Let us now see various methods by which we can make a system to convert sound to electrical energy. The basic parameters that determine the energy characteristics of noise are oscillation frequency and .

Oscillation frequency is represented in Hertz (Hz) and the Figure 1: Propagation of Phonons in Sound sound pressure level is represented by decibels (dB). Such electrical properties include Voltage (V), Current (I), As sound energy is a mechanicalenergy it could be resistance (R) and power (P). These quantities are related to converted into electricity asmechanical energy could be each other as: converted into electricity bythe law of . Sound energy could beeasily converted into energy I=V/R which could be easilyconverted into electricity but it is not P=V2/R ……………………… (1)[10] highly efficient asthe loss in conversion will be more whereas the othermethod is converting sound energy to 3.1 Method 1 electricity by piezoelectric material, piezo electric materials are the crystalwhich converts mechanical strain to electric The first method illustrates the use of the “faradays law of [8] energy bysuch method, fig 2. electromagnetic induction” which states that the induced

electromotive force (Ԑ) in any closed circuit is equal to the So we could see that sound is a form ofmechanical energy negative of the time rate of change of the magnetic flux (Φ) and according to third law ofthermodynamics mechanical through the circuit. energy could be convertedinto electric energy. ε= - dΦB/dt ……………………….. (2)

Sound that is perceptible by humans has frequencies from In this method we will place a very thin layer of diaphragm about 20 Hz to 20,000 Hz. In air at standard temperature and which will be fluctuated by the pressure created by the pressure, the corresponding wavelengths of sound waves sound waves. Now we can attach a conductor to the [8] range from 17 m to 17 mm. diaphragm which will be placed between the magnetic poles. So when the diaphragm oscillates then the conductor will have magnetic flux around it change and as per the faradays law the (emf) is induced in the conductor causing the current to flow to conductor.

Generated voltage (emf) = (Velocity of Conductor) X (Magnetic Field) X (Length of Conductor). ………………………. (3)

As the frequency of the sound waves is high thus oscillations will be fast and considerable amount of electricity could be produced. But only limitation is that we require sound of very high decibels to generate usable quantity of electric [10] Figure 2: Transformation of Energy power.

3. Practical Methods of Conversion

In our day to day life we actually come across various devices that serve the same purpose that is they convert the sound to electrical signals. For example a microphone is an example of a transducer, a device that changes information from one form to another. Sound information exists as patterns of air pressure, the microphone changes this Figure 3: Diaphragm information into patterns of electric current. The recording 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 219 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 3.2 Method 2 is called the direct piezo electric effect, and the crystals that exhibit it are classed as piezoelectric crystal.[12] In this method we could convert sound energy to heat energy as sound wave travel by oscillating the particles of the medium so when sound energy travel through the medium it will disturbs the particle of the medium these disturbance created by sound will be used to convert it into heat energy as when the particles of the medium will be pushed by the sound wave it will collides with adjacent particle of the medium this collision will result production of heat energy the production of heat energy will be more in the denser medium so for more heat production we will need a material with very high density. This heat energy will be converted [11] into electricity. Figure 5: The direct piezoelectric effect

Inversely, when a piezoelectric crystal is placed in an electric field, or when charges are applied by external means to its faces, the crystal exhibits strain, i.e. the dimensions of the crystal Changes.When the direction of the applied electric field is reversed, the direction of the resulting strain is reversed. This is called the inverse piezo electric effect. (See Fig. 6). Figure 4: converting sound energy to electricity

This method is less efficient due to more energy losses taking place while conversion of sound energy to heat energy and then heat energy to electric energy then the other methods. As here the conversion is done two times .you may think that according to Newtown’s law energy can’t be created nor destroyed it could be only converted from one form to another .So while converting sound energy to heat energy there will be some loss of sound energy as some of the sound energy would be converted into another form also Figure 6: The inverse piezo electric effect while converting from heat energy to electric energy all energy wouldn’t be converted into electric energy some of So it could be seen that when the sound energy is applied to the heat energy would get converted into another form of the piezoelectric material it create strain in the crystal then it energy. And here as our main focus is to convert sound reverse it and the strain is converted into electric energy energy to electric energy so conversion into other form of .This direct piezo electric effect property of an piezo electric [11] material could be used for making the device to convert energy is loss of energy for us. sound energy to electric energy.[12]

3.3 Method 3 4. Piezoelectric Crystal Converting sound energy to electricity by Piezo electric material (piezo electric materials are the crystal which 4.1 Energy from Humans convert mechanical strain to electric energy). The human body contains enormous quantities of energy, for 3.3.1 Piezoelectric Materials e.g. an average adult has a one-ton battery in the form of fats Piezo electric materials are transducers its crystals could in present in the body. This energy is used as for all convert mechanical strain to electricity, the crystals are activities. Piezoelectric effect can be used to generate formed naturally e.g. quartz, bone, DNA whereas artificially electricity using such body to run smaller gadgets which consume less power.[12] ZnO, lithium niobatet Lead Metaniobate the sound energy could be converted into electricity using piezo electric material. Let us see the properties of piezo electric 4.2 Present Use of Technology material.[12] Tiles made up of many layers of rubber sheeting, to absorb 3.3.2 Piezoelectric Material andThere Properties the vibrations and ceramic; underneath piezoelectric crystals Certain single crystal materials exhibit the following are placed which can be used to generate electricity by phenomenon: when the crystal is mechanically strained, movements on them. When such tiles are installed in (here sound energy) or when the crystal is deformed by the locations where large crowd movements are expected like in application of an external stress, electric charges appear on Railway & Bus stations, Airports, Malls etc., and a person thecrystal surfaces, and when the direction of the strain steps on them, than by piezoelectric effect small charge is reverses, the polarity of the electric charge is reversed. This built up on surface of crystals.

Volume 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 220 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 Though energy generated by one person would be too less but if number of steps on such tiles increase than energy The reading is collected at Riyadh City in Saudi Arabia, the produced by it would increase too. One more way to specification of the generator power system used the increase energy by use of such tiles is to increase pressure statistical beside mathematical techniques are presented in on them i.e. to use them for road construction. When a this section. The reading collected and relationship between person steps on such tiles piezoelectric crystal underneath it frequency and output voltage are displayed graphically. experiences mechanical stress which creates electric charge built up on crystal’s surface which can be collected by use of 5.1 Instrumentation electrodes. Such energy can be stored in capacitors and power can be channeled to energy deficient regions.[13] The electricity generation experiment was done by using a sound wave convertor extract sound wave energy from the Japan has already started experimenting use of piezoelectric loudspeaker. In this study, PZT piezoelectric actuator, effect for energy generation by installing special flooring shown in fig (8), is used as a sound wave energy convertor. tiles at its capitals’ two busiest stations. Tiles are installed in front of ticket turnstiles. Thus every time a passenger steps on mats, they trigger a small vibration that can be stored as energy.

Energy thus generated by single passenger multiplied by many times over by the 400,000 people who use Tokyo station on an average day, according to East Japan Railway, which generates sufficient energy to light up electronic signboards.[13]

Figure 8: PZT actuator An average person weighing 60 kg will generate only 0.1 watt in the single second required to take two steps across 5.1.1 Design, Coast and Method of Work the tile, but when they are covering a large area of floor This is a speaker with piezoelectric actuator formed from space and thousands of people are stepping or jumping on lead zirconate titante (PZT) ceramic, the PTZ is the white them, then significant amount of power can be generated. disk in the center of a brass diaphragm. The PTZ coated with This energy created is sufficient to run automatic ticket gates a thin silver layer on the top as one electrode, and the brass and electronic displays, constructing special types of roads is used as the bottom electrode. When the generated sound that generates electricityjust by driving over them is next wave from the motion of the diaphragm in the loudspeaker is step towards use ofpiezoelectric crystals. The system works applied to the piezoelectric actuator, a pressure wave is by embedding tinypiezoelectric crystals into the road,when produced that hits the piezoelectric actuator. Sufficient cars drive over suchroads crystals embedded in them energy from this generated sound can deform the squeeze and thus generate asmall electrical charge. Though piezoelectric actuator and generate electricity. This small charge is generated bysingle car but 1 km stretch of electricity, which is in the form of voltage signal, is such road could generate around400kW-enough to run eight measured using an oscilloscope. The device has been bought small cars. about 30 $.

According to the EnvironmentalTransport Association To verify the resonant frequency of the piezoelectric (ETA), if such system was installed onevery stretch of actuator, the frequency of the sound wave used is increased British motorway it would generate enoughenergy to run gradually from 50 Hz to 70 Hz for the first mode, and from 34,500 small cars. Certain vehicles could thus bepowered [14] 360 Hz to 390 Hz for the second mode. During resonance, entirely by road on which they drive. the maximum conversion produces the highest voltage as a result of the piezoelectric effect, also the effect of the distance between the sound source and the piezoelectric during resonance is investigated.

Figure 7: Specially designed road which generates electricity.

5. Material and Method

This section is devoted for the equipment and instruments Figure 9: Sketch of the experimental used in relating the frequency and output voltage, for the system generate electricity test.

Volume 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 221 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 5.2 Data Collection: Criteria and Requirement sound intensity, resonant frequency and output voltage are collected. The following study was carried out as applied experimental study in the realm of applied physics science inclusively as To obtained data related to frequency were plotted versus renewable energy. output voltage in first and second mode. The significant relationships are examined by using Statistical Package The resonant frequency Social Science version 20(SPSS – 20). 1/2 ƒ0=(1/ 2π) (kT/ meff) ………………….. (4) Where: ƒ0= resonant frequency of actuator [Hz] 6. Results and Discussion kT = piezo actuator stiffness [N/m] meff = effective (about 1/3 of the mass of the ceramic Table and Graph stack plus any installed end pieces) [kg] Table 1, First Mode (50 – 70) Hz The small-signal capacitance of a stack actuator can be estimated by: Table 1: Resonant frequency in the first mode C = n. ε33. T . A/ds ……………………….. (5) Distance Resonant Sound Output voltage (cm) Frequency Intensity (mVrms) Where: (Hz) (dB) C = capacitance [F (As/V)] 1 65 80.5 28.8 n = number of layers = I0 / ds 4 66 77.4 15.6 ε33T = dielectric constant [As/Vm] 7 69 76 10.7 A = electrode surface area of a single layer [m2] dS = distance between the individual electrodes (layer- Table 2, Second Mode (369 – 390) Hz thickness) [m] [15] I0 = actuator length. Table 2: Resonant frequency in the second mode Distance Resonant Sound Output To a chive these objectives, the research was carried at (cm) Frequency Intensity voltage Riyadh City – Saudi Arabia, during the period from January (Hz) (dB) (mVrms) 1 378 105. 5 94 2015 to April 2015. When reading are subjected to 4 379 100. 7 65. 7 experiment test information such as, distance from source, 7 381 90.6 35

Graph: First mode (50 – 70) Hz

Figure 10: Relationship between frequency and output voltage at 1 cm, first mode.

Volume 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 222 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611

Figure 11: Relationship between frequency and output voltage at 4 cm first mode.

Figure 12: Relationship between frequency and output voltage at 7 cm first mode.

Graph: Second mode (360 – 370) Hz

Figure 13: Relationship between frequency and output voltage at 1cm, second mode. Volume 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 223 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611

Figure 14: Relationship between frequency and output voltage at 4 cm, second mode.

Figure 15: Relationship between frequency and output voltage at 7cm, second mode.

7. Discussion The output voltage obtained from the experiment shows that at the resonant frequency of each state, 28.8 mVrms at 1 cm, Table (1) and figs. (10, 11 and 12) the resonant frequencies 15.6 m Vrms at 4 cm and 10.7 mVrms at 7 cm are produced in obtained are 65 Hz, 66 Hz and 69 Hz at 1, 4 and 7 cm, the first mode, as in figs. (10, 11 and 12). respectively. In the second mode, as shown in Table (2), the resonant frequencies occur at 378 Hz, 379 Hz and 381 Hz at Figs. (13, 14 and 15) shows that in the second mode, the 1, 4, 7 cm, respectively. voltage produced are 94 mVrms at 1 cm, 65.7 mVrms at 4 cm and 35 mVrms , which are higher than those produced in the Sound intensity is measured at different distances, and the first mode. When the piezoelectric actuator is placed near results are 80.5 dB at 1cm, 77.5 dB at 4 cm and 76 dB at 7 the speaker, the pressure gradient and frequency of sound cm. In the second mode, the sound intensities obtained are wave are higher, thus a considerable amount of energy is 105.5 dB at 1 cm, 100.7 dB at 4 cm and 90.6 dB at 7 cm. applied to increase the deformation of the piezoelectric These results show that when the piezoelectric actuator is actuator. As a result, maximum voltage is produced by the placed near the sound source, the pressure gradient of the piezoelectric. sound wave is at maximum, thus, for both modes, sound intensity increases as the distance decreases.

Volume 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 224 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 8. Conclusion Journal of Scientific & Engineering Research ISSN 2229-5518, Volume 5, Issue 1, January 2014.  Sound energy is a mechanical energy so according to law [11] Jos Arrillaga and Neville R. Watson, “Power System of thermodynamics mechanical energy could be Harmonics”, John Wiley & Sons Ltd. England, 2003. converted into electric energy. [12] Shalabh Rakesh Bhatnagar ” converting sound energy to  Sound energy could be converted by different methods: electric energy” International Journal of Emerging  Method 1 by creating apparatus using curtain Technology and Advanced Engineering ISSN 2250- (diphagram) magnet and conductor 2459, Volume 2, Issue 10, October 2012. [13] Henry Frank Tiersten “Linear Piezoelectric Plate",  Methods 2 by converting Sound energy to heat energy Springer Heidelberg Dordrecht London and New York, and then heat 1969.  Energy to electric energy. [14] Tanvi Dikshit, Dhawal Sheerivastava, Abhijeet Gorey,  Method 3 by using transducers such as piezoelectric Ashish Gupta, Parag Parandkar and Sumant Katiyal, material which converts mechanical strain to electric “Energy Harvesting via Piezoelectricity" BVICAMs energy. International Journal of Information Technology, 2010.  Piezo electric crystals are the crystals which converts [15] Pramathesh. T and Ankur. S “Piezoelectric Crystals: mechanical strain to electric energy. Future Source of Electricity"International Journal of  The strain applied to piezo electric material by sound Scientific Engineering and Technology ISSN 2277- energy could be converted into electricity. 1581, Volume 2, Issue 4, April 2013.  Use of piezoelectric crystals has being started and [16] Zhu D, Beeby SP, “Energy Harvesting Systems - positive results are obtained. With further advancement Principles, Modeling and Applications”, Springer New in field of electronics, better synthesized piezoelectric York, 2011. crystals and better selection of place of installations, more electricity can be generated and it can be viewed as a next promising source of generating electricity.  This study therefore show that the proposed technique used to harvest sound wave energy is relevant and has great potential in terms of converting free energy into useful energy.  Sound intensity is an important parameter to effectively extract and convert energy using a piezoelectric actuator.  Results show that less voltage is produced as distance increases.

References

[1] V. K. Vijay and H. R. Garg, “ Renewable Energy and Environment for Sustainable Development " , 2009 [2] William Kemp, “Renewable Energy Handbook”, AZ text Press, 2003. [3] K. C. Singal, Rakesh Ranjan, D. P. Kothari, “Renewable Energy Sources and Emerging Technologies,” PHI Learning Ltd. India, 2011. [4] Antonio Arnau “Piezoelectric Transducers and Applications", Springer – Verlag Berlin Heidelberg, German and Spain, 2008. [5] Md. Mostaqim Billah Arnab, Shah Md. Rahmot Ullah, Md. Ashraful Alam, Raton Kumar, S M. Forhadul Alam and Anik Paul Mish, “Generation of Electrical Energy Using Piezoelectric Material from Train Wheels: Bangladesh Perspective" , IEEE [6] ISSN978-4799-6062-0/14/$31.00, 2014. [7] J. Duncan Glover, Mulukutla S. Sarma and Thomas Overbye, “Power System Analysis and Design,” CENGAGE Learning, USA, 2011. [8] Simon M. Sze and Kwok K. Ng “Physics of Semiconductor Devices”, John Wiley & Sons, Inc. Press, New York and London, 2006. [9] Bernard Jaffe, W. R. Cook and H. Jaffe “Piezoelectric Ceramic,” Academic Press London and New York, 1971. [10] Alankrit Gupta, Vivek Goel and Vivek Yadav, “ Conversion of Sound to Electric Energy "International Volume 5 Issue 1, January 2016 www.ijsr.net Paper ID: NOV152677 Licensed Under Creative Commons Attribution CC BY 225